Pawpaw tree named ‘Levfiv’

ABSTRACT

Disclosed herein is a new and distinct variety of pawpaw tree, which has been given the name ‘Levfiv.’ This variety is distinguished by its all-around excellent fruit quality consisting of large, firm, fleshy, thick skinned fruits with an unusually low seed-to-fruit ratio and an excellent flavor. This variety possess the fleshiest and firmest fruit in pawpaws found to date. The texture is firm and smooth. The number of fruit per cluster is low, often in singles, which simplifies harvesting. The fruit possesses a color break at picking stage which is a major advantage in harvesting the fruit. The fruit firmness plus the thick skin will help in shipping and handling. This variety is one of three varieties newly identified as having potential to establish a commercial pawpaw industry.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct and superior varietyof the pawpaw which is of interest for its fruit.

The species—Asimina triloba (L.) Dunal—is the largest native ediblefruit of North America, a member of the Annonaceae family, and thus arelative of the cherimoya, sweetsop, guanabana and custard apple (Annonacherimola, A. squamosa, A. muricata and A. reticulata), all of which arepopular fruits that are widely cultivated in tropical and subtropicalregions of the world, including southern Florida and southernCalifornia. The pawpaw is the only truly temperate member of theAnnonaceae, being indigenous to a region stretching from the Great Lakesto the Gulf Coastal Plain and from the Chesapeake Bay to the GreatPlains.

Currently, the pawpaw is considered to be semi-domesticated. NativeAmericans casually cultivated the tree, as did the white settlers whodisplaced them. The selection, propagation and naming of pawpawvarieties from the wild has been practiced for more than a century, andthe backyard cultivation of pawpaws for personal use is not uncommon inAppalachia and parts of the Midwest. Numerous unregistered, unpatentedvarieties are available in the mail-order nursery trade.

Commercial cultivation of pawpaw has not developed, however. The fruitis fragile and highly perishable which makes transport difficult. Andscientific attention towards improving the fruit, its culture and itspostharvest handling has been neglected until recently. The lack of highquality cultivars that meet the requirements of producers and consumersis the foremost reason that commercial cultivation has not beenundertaken.

The present invention, named ‘Levfiv,’ is one of three new and distinctvarieties of pawpaw each of which represents a great improvement overexisting pawpaw varieties because of higher yields, superior flavor,fewer seeds and firmer flesh. The other two varieties are ‘Aidfievate’,which is the subject of co-pending application Ser. No. 09/954,140, and‘Wansevwan’, which is the subject of co-pending application Ser. No.09/954,536. These varieties possess the minimum overall qualitiesrequired for the development of a commercial pawpaw industry. Theprimary use of this pawpaw variety will be for fresh eating as a dessertfruit. Secondary use will be in processed products such as ice cream,yogurt, juice and cosmetics. Of the three, the variety ‘Levfiv’ isoutstanding for combining large fruit size with high firmness, greatfleshiness and good flavor.

ORIGIN

The variety ‘Levfiv’ was developed by R. Neal Peterson as the result ofa breeding project to improve the pawpaw, which he began in 1980. Theproject was conducted during a period when Peterson was employed as aneconomist with the Economic Research Service of the United StatesDepartment of Agriculture in Washington, D.C. However, because Petersonwas not employed in any capacity as a horticulturist or other researcherin the biological sciences, and no Department of Agriculture plantstock, facilities or information was used, the United States governmenthas no interest in the rights to the claimed variety.

The germplasm for Peterson's breeding project came principally from thesurviving remnants of five historic collections of pawpaw dating to theearly twentieth century that were the work of the most prominent pawpawcollectors and breeders of the time, and whose named material was nolonger propagated or otherwise available. In 1982 germ plasm[open-pollinated seed] was collected from these remnants and includedwith open-pollinated seed from named cultivars, which became the germplasm for his own breeding and selection work.

In 1983 the seed was germinated and in the following spring 808accessions were planted at the University of Maryland experimentstation, the Wye Research & Education Center, Queenstown, Md. Sincethen, the orchard has been supervised by the inventor, with basic staffsupport from the university. Basic tasks such as fertilizing, sprayingand mowing were conducted by the station staff. The inventor pruned,weeded, and collected data on growth rates, flowering, fruit set,yields, cluster size, fruit size and fruit quality, including data fromtaste panels which he organized.

In 1991, the inventor analyzed four years of data, and concluded inidentifying eleven trees as superior for further study. Nine of theseare involved in regional variety trials around the country and have beentermed advanced numbered selections. After nine additional years ofobservation, the original nine were narrowed to three that wereconsistently of the highest quality. One of these bears the accessionnumber PPF 11-5 and is the variety that is the subject of thisapplication. The original tree PPF 11-5 is 18 years old. This newvariety, named ‘Levfiv,’ originated as an open-pollinated seedling froma pawpaw tree on the grounds of the Blandy Experimental Farm, Boyce,Va., which tree was given the label BEF-53 by the inventor. PawpawBEF-53 is believed to have been a cataloged accession of the BlandyExperimental Farm's collection of Asimina triloba (circa 1922-1955)although records to support this contention are now missing. To ourknowledge BEF-53 has never been asexually propagated.

ASEXUAL REPRODUCTION OF THE VARIETY

In 1994, the inventor began topworking the Wye orchard to his elevenadvanced numbered selections, plus named varieties. Topworking wasaccomplished using bark-inlay grafting and chip-budding. Grafting of‘Levfiv’ was easy by either method, and gave a high percentage ofsuccess. Replicates of ‘Levfiv’ now number more than 20 at the Wye,having been propagated through successive cycles of grafting over sevenyears. The rootstock for these grafts were mature seedling pawpaw treesgrowing in the orchard, and were a portion of the original accessionsfrom 1983, described previously. Four grafted trees of ‘Levfiv’ have nowbeen in bearing since 1997 and demonstrate that asexual reproduction ofthis new and distinct variety preserves the desirable characteristics ofthe variety and establishes and stably transmits those characteristicsthrough successive propagation at the Queenstown location.

SUMMARY OF THE VARIETY

‘Levfiv’ possesses exceptional fruit quality, combining as it does in asingle variety large size, firm texture, very few seeds and excellentflavor. The fruit is extremely large, on average 300 gm forwell-pollinated fruit, and may exceed 450 gm. The cluster size varies,but is commonly one, two or three fruited. Fruit shape is broadlyellipsoidal to nearly spherical. The skin is thicker and tougher than istypical for the species. Skin color is pale yellow-green and slightlyglaucous, and is uniformly speckled with minute black dots the size ofpin pricks. The fruit normally exhibits a color-break at the stage forpicking, which is visible as a brownish collar around the neck of thefruit. This color break is reliable and can be easily discerned withpractice. The composition of the fruit is extremely fleshy, with manyfewer seeds relative to fruit weight than is typical of pawpaw. Seedsize is large. The aroma of the fruit before and after cutting ispleasant and mild. The flavor is excellent, though not as good as‘Wansevwan’—mild, sweet, free of bitterness or astringency, with apleasant aftertaste. The pungent asiminous component that is uniquelypawpaw and that many people find objectionable is very low. The flesh isvery firm and very smooth with a consistency resembling ‘Haas’ avocado,and produces a very pleasant mouth-feel. It has no detectable fiber orgrit. The ripening period at Queenstown has been mid to late season,September 12 to 27, more or less, depending on the degree of heat in thepreceding months.

Several non-fruit characters of ‘Levfiv’ also serve to distinguish itfrom other pawpaws. For the most part, leaf characters (size, color,shape and aspect) are typical of pawpaw. Unlike typical pawpaw, however,the upper surface of the leaf is distinctly rugose. This rugoseness,though not pronounced, is evident in both young and mature leaves, andis a trait unique to ‘Levfiv’ plus a few other progeny from the samemother tree, BEF-53. The petioles are shorter than usual for thespecies. The branching habit is widely spaced with wide crotch anglesnormally. Flower measurements when taken as a whole may identify‘Levfiv’ though perhaps not uniquely. Its flowers are medium in size,outer petals orbicular, and are notable for having petals that are notas recurved and flaring in the male stage as is typical for the species.For exact data, see the detailed description and accompanyingphotographs.

This variety is susceptible to Talponia plummeriana, the pawpaw pedunclemoth, is susceptible to Eurytides marcellus, the zebra swallowtailbutterfly, and is believed to be susceptible to pawpaw decline disease,the same in all cases as the species. This variety does not requirepruning except to control ultimate tree size. It responds well topruning, forming a broadly spreading tree of globular shape withnormally wide crotch angles. Pruning has an invigorating effect thatstimulates growth and fruit bearing. Corrective pruning is minimal. Treevigor is less than most pawpaws and this variety may need to be graftedonto more vigorous rootstocks to promote good growth and heavierbearing. Fruit yields are moderate, somewhat less than ‘Wansevwan.’

BRIEF DESCRIPTION OF THE DRAWING

In the accompanying drawings, leaves, flowers, fruits and seeds areshown in color that is as nearly true as is reasonably possible to makein color photographs of this nature. The deep maroon hues of the flowersare the most difficult for photoemulsions to render accurately.

FIG. 1 Shows the fruit of the new variety, hanging on the tree.

FIG. 2 Shows the fruit of the new variety in dissection, revealing thecolor, fleshiness and seeds.

FIG. 3 Shows the flower of the new variety in the female stage, inprofile and dissection.

FIG. 4 Shows the flowers of the new variety in the male stage, inprofile and dissection.

FIG. 5 Shows the habit of a pruned tree of the new variety.

FIG. 6 Shows a close-up of the leaves of the new variety.

BOTANICAL DESCRIPTION

Because no variety of Asimina triloba has had application made to thePatent Office, we include a botanical description of the species drawnfrom two taxonomic authorities, C. S. Sargent and R. Kral.

Shrub or small tree 1.5-11 (˜14) m tall from a stout, sometimes branchedtaproot, with a straight trunk seldom exceeding 30 cm in diameter; thebark of older trees gray-brown, shallowly furrowed, and marked withlarge ash-colored blotches; that of new shoots moderately to copiouslydark brown-hairy toward the summit, aging smooth, gray-brown; wintervegetative buds naked, without stipules, acuminate and dark brown torusty brown-hairy, 2-5 mm long, and tightly appressed against the stem;winter flower buds globose, dark brown-hairy, 2.5-5 mm in diameter;leaves membranaceous, oblong-obovate to oblanceolate, 15-30 cm long;apex acute to acuminate; base more or less gradually attenuate to theshort (0.5-1 cm) petiole; margin flat or scarcely revolute; youngsurfaces sparsely appressed reddish-pubescent above; densely so beneath,becoming glabrous above and sparsely hairy on the veins beneath; flowersgreen initially, then turning brown to maroon to deep vinous red, 2-5 cmbroad with a faintly fetid aroma, on densely dark brown-hairy, noddingpeduncles 1-2.5 cm long which develop from the axils of the prominentleaf scars; calyx 8-12 mm long, of three triangular-deltoid sepals whichare striate with brown hairs on the outside, glabrous within; outerpetals 1.5-2.5 cm long, oblong-elliptic, with ascending bases andslightly to conspicuously recurved tips, copiously appressed-hairy alongthe veins outside, glabrous and impressed-veiny within; inner petals ⅓-½the length of the outer, elliptic, saccate-based, recurved tipped,glabrate without, glabrous and impressed-veiny within, with a corrugatednectary zone usually of a lighter color; androecium globular, 0.5-1 cmbroad, pale green at anthesis; gynoecium of 3-10 fusiformappressed-red-hairy carpels; fruits oblong-cylindric, 5-15 cm long,yellow-green to brownish when ripe, attached obliquely to the enlargedtorus of the peduncle in clusters of variable number; seeds 1.5-2.5 cmlong, brown to castaneous, shiny when mature, bean-shaped, somewhatlaterally compressed, contained within an aril that is confluent withthe pericarp from which the seed readily separates.

DETAILED DESCRIPTION OF THE INVENTION

Following is a detailed description of the new variety of pawpaw treewith color terminology in accordance with The Royal Horticulture Society(R.H.S.) Colour Chart (Ed. No. 2, 1986) except where general color termsof ordinary dictionary significance are used.

-   Tree:    -   -   Size.—Medium. 4.5 m on its own roots but taller on more            vigorous rootstock.        -   Vigor.—Low to medium when grafted onto other rootstock.            Approximately 42 cm growth on strong primary laterals under            standard fertilization of 50 lbs of N per acre.        -   Habit.—Rounded with age, but taller than broad in the            unpruned condition.        -   Branching pattern.—Spreading. Crotch angles wide. Branches            widely spaced.        -   Apical dominance.—Medium.        -   Trunk.—Diameter 14.6 cm measured at 30 cm above ground            level.        -   Bark.—Smooth with small raised horizontal lenticels, typical            of the species. Color between R.H.S. Greyed-Green 197A and            Grey 201B on both trunk and branches.-   Leaf buds:    -   -   Length.—Axillary buds growing on branches of normal vigor,            3.8 mm average with a range of 3.2 to 4.5 mm. Buds growing            on branches of high vigor larger, 5.9 mm average with a            range of 4.5 to 7.4 mm.-   Leaves:    -   -   Shape.—Oblanceolate with acuminate tip and attenuate to the            base, as is typical for the species. Average ratio of width            to length is 0.490.        -   Size.—Measurements are from mature leaves attached at            midpoint of actively growing shoots of current season's            growth. Average size is 13.5 cm wide, 27.5 cm long.        -   Color.—Upper surface varies from R.H.S. Green 139A to            Yellow-Green 147A. Lower surface R.H.S. Yellow-Green 146A.            Both colors typical for the species.        -   Aspect.—Drooping when grown in full sun, as is typical for            the species.        -   Margin.—Entire.        -   Texture.—Upper surface slightly but distinctly rugose, very            atypical for the species.        -   Arrangement.—Alternate opposite.        -   Petiole.—Color yellow-green similar to lower leaf surface.            Average diameter 3.3 mm at the petiole midpoint. Length            ranges from 10.0 to 12.9 mm with an average of 11.4 mm.            NOTE: The structure of the leaf lamina is such, in the way            that it tapers gradually to the petiole, that visual            demarcation of the petiole terminus is imprecise and the            resultant measurement of petiole length has a high margin of            error. The measurements reported here are based on a tactile            method that is more precise. By means of running the back of            one's thumbnail down the midvein (on the underside of the            leaf) towards the petiole one encounters a sudden change in            curvature, diameter, and hardness. This point of change is            the petiole terminus and is easy to detect and replicate.-   Flower buds:    -   -   Size.—Length 4.8 mm average. Width 4.2 mm average.        -   Appearance.—Very dark brown, between R.H.S. Brown 200A and            Black 202A. Surface densely pubescent, velvety.-   Flower:    -   -   Size.—Medium to small. As the flower matures from female to            male stage, the petals reflex, and therefore measured flower            size is specific to flower stage, which data are presented            below.        -   Outer petals.—Average of 26 mm wide, 28 mm long. Average            ratio of width to length is 0.93.        -   Inner petals.—Average of 13 mm wide, 19 mm long. Average            ratio of width to length is 0.67.        -   Color.—Maroon.        -   Form of female stage flower.—Slightly less closed than            typical.        -   Size of the female stage flower.—Diameter 27 mm average.        -   Nectary band of female stage flower.—Reddish-maroon color,            not as dark as surrounding inner petal.        -   Form of male stage flower.—Outer and inner petals recurved            and only slightly more flaring than in the female stage,            much less so than typical for pawpaw.        -   Size of the male stage flower.—Diameter 35 mm average.        -   Nectary band of male stage flower.—A deep maroon color,            basically indistinguishable from the inner petal color.        -   Peduncle.—Short, average length 10 mm. Lightly pubescent            with dark brown hairs.-   Fruit:    -   -   Dates of picking.—Mid to late season, generally from            September 12 to 27 at Queenstown, but dates can vary by more            than a week depending on the degree of summer heat.        -   Cluster size.—Few fruited. One, two and three-fruited            clusters are prevalent, and this small cluster size is            atypical of pawpaw. Larger clusters occur, however, even            exceeding five fruits. Within large clusters the fruit size            typically varies considerably. High within-cluster variance            of fruit size is common in pawpaw.        -   Fruit shape.—From broadly ellipsoidal to somewhat            cylindrical with rounded ends. Shape varies considerably;            but large well-formed fruit in a single-fruited cluster tend            towards length-to-width-to-depth proportions of 100:73:70.        -   Fruit size.—Very large, 300 gm average for well-pollinated            fruit. Much larger than typical pawpaw. Size varies from            small (˜42 gm) to very large (˜500 gm), dependent on the            number of fertilized seed present in the fruit. Lengths            normally range 5.5-13.0 cm, widths 4.0-9.5 cm, and depths            3.8-9.0 cm.        -   Suture.—Fine green line, usually present.        -   Abcission type.—Primary mode is for fruit to abscise from            the torus of the peduncle.        -   Abscission scar.—Large, 10.8 mm in diameter. A character of            low variance.        -   Peduncle.—Length 18.7 mm on average, ranging from 16.0 to            21.5 mm. Diameter extremely variable, varying in proportion            to the cluster fruit mass, as is typical of the species.            However, in comparison to the range of peduncle sizes of            pawpaw cultivars, and relative to the total cluster fruit            weight, the diameter is thick. Peduncle pubescence dark            brown, varies from dense to sparse, typically dense. The            point of peduncle attachment to single-fruited clusters is            near the central axis of the fruit, slightly offset to the            dorsal side.        -   Skin color.—Under-ripe fruit pale green and glaucous,            ranging from R.H.S. Yellow-Green 144A to 145B. Ripe fruit            pale yellowish green and glaucous, R.H.S. Yellow-Green 152D.            Skin speckled with closely spaced tiny black dots the size            of pin pricks. After the fruit passes its climacteric peak            and falls from the tree, brown blotches appear which spread            to cover the entire skin surface, as is typical for the            species.        -   Color break.—Above noted color change is basically reliable.            In addition, in most years, a brown collar develops around            the “neck” where the fruit attaches to the peduncle. This            color break precedes browning of the skin anywhere else on            the fruit and is a reliable sign that the fruit is ready to            pick.        -   Skin thickness.—Medium-thick and tough.        -   Aril.—Thin, tender, and edible.        -   Fleshiness.—Very high. Percent seed is 3.3 on average. The            average quantity of pulp per seed is 34.8 gm.        -   Flesh color.—Creamy yellow and uniform throughout. Color            ranges from R.H.S. Yellow-Orange 21B to 22B.        -   Aroma of uncut fruit.—Pleasant. Low power.        -   Aroma of cut fruit.—Pleasant. Low power.        -   Flavor.—Very sweet, Brix 26%, mild, nonbitter, and            nonastrigent. Pungent asiminous component low.        -   Aftertaste.—Pleasant, long lingering, no negative            components.        -   Consistency.—Flesh is very firm (very atypical of pawpaw)            and very smooth, closely resembling ‘Haas’ avocado in            texture and consistency. Melting in the mouth. Pleasant            mouth-feel. No detectable fiber or grit.        -   Use.—Principally for fresh eating as a dessert fruit.            Secondarily in processed products.-   Seed:    -   -   Size.—Large. 1.40 gm average weight. Dimensions 24.0 mm            long, 14.6 mm wide, 7.1 thick on average.        -   Color.—Dark brown. R.H.S. Brown 200A.        -   Number per fruit.—7 per average fruit of 300 gm. As fruit            size varies greatly in pawpaw, the seed number per fruit is            not a stable character, unlike the seed-to-fruit ratio            (percent seed) which is stable.-   Physiological and ecological characters:    -   -   Graftability.—Very easy to graft by virtually all methods.            Percent take is medium to high for pawpaw, in vicinity of            85-95%.        -   Habit of tree after grafting.—Medium vigor. Time to            flowering on established rootstock is roughly three years.            It appears that common seedling rootstocks have more vigor            than the tree's own roots.        -   Pruning.—The tree responds well with moderate vigor to            pruning. Flowering and general vigor improved by pruning.        -   Flower count.—Medium to high. Average of 4.5 blossoms per            branch on vigorous branches, but flower number varies            considerably depending on vigor of the branch.        -   Self-fruitfulness.—Requires cross pollination.        -   Bearing.—Annual and consistent.        -   Fruit set.—Low, less than 15 percent in most years.        -   Yields.—High. From mature trees approximately 30 lbs. of            fruit per tree. At orchard densities of 330 trees per acre,            this is 10,000 lbs per acre.        -   Keeping quality of fruit (normal storage, 24° C.).—Short.            Three days when ripe. Typical for the species.        -   Keeping quality of fruit (cold storage, 2° C.).—Moderate.            Three weeks when picked at the proper time of color break.        -   Shipping quality of fruit.—Medium to good if shipped            refrigerated with adequate cushioning. Poor otherwise            because of the rapid ripening which is typical for pawpaw.        -   Resistance to Talponia plummeriana.—Susceptible.        -   Resistance to Eurytides marcellus.—Susceptible.        -   Resistance to pawpaw decline disease.—Believed to be            susceptible.-   Variance in botanical details: The pawpaw tree and its fruit    described herein will vary due to climate, soils, growing conditions    and culture.

1. A new and distinct variety of pawpaw tree, obtained as anopen-pollinated seedling of BEF-53 (unpatented), substantially as shownand described herein.